Neuroscientists have long recognized the significance of using microelectrode arrays for recording extracellular potentials from populations of neurons, for which a number of such devices have been developed so far. However, current implantable microelectrode technologies to monitor single neuronal function in-vivo often fail in chronic situations, likely due to mechanical drift in positioning mechanisms, micromotion of brain tissue and gliosis around the implant site. The overall goal of this competitive revision (Notice Number NOT-OD-09-058 and Notice Title: NIH Announces the Availability of Recovery Act Funds for Competitive Revision Applications) is to develop a reliable technology for recording electrical potentials from ensembles of single neurons and neuronal networks in chronic experiments. Our parent grant is focused on developing a novel microfabricated thermal microactuator and associated microelectrode technology in collaboration with Sandia National Laboratories to enable repositioning of microelectrodes after implantation. The flexibility to reposition the microelectrodes after implantation (in the event of a failure or otherwise) using microactuators will potentially increase the reliability and consistency of single-neuronal recordings in-vivo in chronic experiments with awake and behaving animals. This competitive revision will run concurrently with the last two years of the 4 year parent grant. The specific aims of this proposed 2-year effort are (a) to design, develop and test two novel core technologies for creating 3D stacks of microchips with moving mechanical parts that will allow us to build a 3D cluster of independently movable microelectrodes and b) to validate the most optimal 3D cluster of movable microelectrodes in chronic rodent experiments. We will use a combination of modeling and simulation, novel microfabrication and packaging techniques, bench-top testing and in vivo testing approaches for design, characterization and validation. Besides leading to novel discoveries in our own research into neuronal mechanisms of plasticity, this new technology will immediately impact several NIH funded grants of our collaborators. Independent evaluation and dissemination will be ensured with the help of collaborators doing in vivo experiments for understanding the mechanisms of memory retrieval and consolidation and memory deficits in aging, auditory physiology, cortical prostheses etc. PUBLIC HEALTH RELEVANCE: Successful completion of the proposed project will result in the development of a novel technology that will allow us to reliably and consistently monitor the activity of individual neurons in the brain. Current technologies fail in long-term experiments and clinical situations. The proposed technology will therefore have a significant impact in improving the success of emerging brain prostheses technologies besides facilitating key discoveries in long-term Neurophysiological events.